Leopard Shark

fieldmarks: Unique large sharks that combine a broad, low caudal fin about as long as the rest of the shark with nasoral grooves, barbels, a small transverse mouth in front of the lateral eyes, two spineless dorsal fins and an anal fin, the first dorsal fin much larger than the second and with its origin far forwards on back, prominent ridges on the sides of the body but no strong lateral keels on the caudal peduncle. Colour: colour pattern banded or spotted. Young sharks are dark brown above, yellowish below, with vertical yellow stripes and spots breaking the dorsal coloration into dark saddles; in specimens between 50 and 90 cm length the saddles break up into small brown spots on a yellow background, these becoming less linear and more uniformly distributed with further increase in size. There is considerable variation in the colour pattern between individuals of like size. An albino specimen was once collected. Head broad, conical and somewhat flattened, without lateral flaps of skin. Snout very broadly rounded or truncated. Eyes laterally situated on head and without strong subocular ridges below them. Eyes without movable upper eyelids or subocular pockets and ridges. Spiracles large and subequal to eyes, without prominent raised external rims; spiracles behind but not below eyes. Gill slits small, fifth gill slit overlapping fourth; internal gill slits without filter screens. Nostrils with short pointed barbels but without circumnarial folds and grooves around incurrent apertures. Nasoral grooves long and strongly developed. Mouth moderately large, nearly transverse and subterminal on head. Lower lip trilobate and with lateral orolabial grooves connecting edge of lip with medial ends of lower labial furrows, no longitudinal symphysial groove on chin. Lower labial furrows ending medially far lateral to symphysis, not connected medially by a mental groove or groove and flap. Teeth not strongly differentiated in upper and lower jaws, with symphysial teeth not enlarged nor fang-like. Tooth row count 28 to 33/22 to 32. Teeth with a strong medial cusp, a pair of short lateral cusplets, and weak labial root lobes. Teeth orthodont with a central pulp cavity and no plug of osteodentine. Body cylindrical, with strong ridges on sides. Precaudal tail shorter than body. Caudal peduncle without lateral keels or precaudal pits. Pectoral fins large, broad and rounded. Pectoral fins semiplesodic and with fin radials partly expanded into fin web. Pectoral propterygium small and separate from mesopterygium and metapterygium; pectoral-fin radial segments three to nine, and with longest distal segments up to 1.3 times the length of longest proximal segments. Pelvic fins smaller than first dorsal fin but larger than second dorsal fin and as large or larger than anal fin, much smaller than pectorals and with anterior margins 0.4 to 0.6 times the pectoral-fin anterior margins. Claspers poorly known but probably without mesospurs, claws or dactyls. Dorsal fins with second dorsal much smaller than first. First dorsal-fin origin expanded well ahead of pelvic-fin origins and with insertion about over pelvic-fin bases. Anal fin larger than second dorsal fin, with broad base, angular apex, origin about opposite second dorsal-fin midbase or insertion, and insertion separated by a space or narrow notch much less than base length from lower caudal-fin origin. Caudal fin greatly elongated horizontally and not crescentic, weakly heterocercal with its upper lobe at a low angle above the body axis; dorsal caudal-fin margin about half as long as the entire shark. Caudal fin with a strong terminal lobe and subterminal notch but without a ventral lobe, preventral and postventral margins not differentiated and forming a continuous curve. Vertebral centra with well-developed radii. Total vertebral count 207 to 243, monospondylous precaudal count 43 to 49, diplospondylous precaudal count 38 to 50, diplospondylous caudal count 120 to 154, and precaudal count 81 to 101. Cranium broad and expanded laterally. Medial rostral cartilage moderately long and not reduced to a low nubbin. Nasal capsules elevated and not greatly depressed or fenestrated, internarial septum moderately high and slightly compressed. Orbits with small foramina for preorbital canals, medial walls not fenestrated around the optic nerve foramina. Supraorbital crests present on cranium and laterally expanded and pedicellate. Suborbital shelves moderately broad and not greatly reduced. Cranial roof solid, without a continuous fenestra from the anterior fontanelle to the parietal fossa. Basal plate of cranium with a pair of stapedial foramina widely separated from medial carotid foramina. Adductor mandibulae muscles of jaws with two divisions. Preorbitalis muscles extending onto posterodorsal surface of cranium. No anterodorsal palpebral depressor, rostromandibular, rostronuchal or ethmonuchal muscles. Valvular intestine of ring type with 18 turns.

Indo-West Pacific: From the east coast of South Africa (Eastern Cape and KwaZulu-Natal Provinces), Mozambique, and Madagascar north to Tanzania and east to the Red Sea, Gulf of Aden, the Maldives, the Persian Gulf, Pakistan, India, Sri Lanka, Bangladesh, Malaysia (including Sarawak, Borneo), Singapore, Indonesia (Java, Macassar Strait, Sulawesi, Dobo and Aru Islands), Thailand, Viet Nam, Kampuchea, Philippines, China, Taiwan (Province of China), Japan, New Guinea, northern Australia (Western Australia, Northern Territory, Queensland, New South Wales), New Caledonia, and Palau.

Maximum possibly 354 cm, but most adults apparently below 2.5 m. Young hatching at a size between 20 and 36 cm; males maturing between 147 and 183 cm; females maturing between 169 and 171 cm and reaching at least 233 cm.

This is an inshore tropical shark of the continental and insular shelves of the Indo-West Pacific, that is very common on coral reefs but also occurs offshore on soft grounds.It ranges from the intertidal down to 62 m. It has been reported from fresh water in Philippines, but this needs to be confirmed. Adults and large spotted juveniles prefer lagoons, channels and faces of coral reefs, reef detritus and sandy places as rest areas, but the striped young are rarely seen and may prefer water below 50 m. The biology of the zebra shark is sketchily known despite being relatively common and readily observed alive by divers on coral reefs and as catches in Indo-West Pacific fish markets. The behaviour and social organization of this shark is little known, but it has been photographed resting on sandy areas within reefs, sometimes propped up on its pectoral fins and facing a current with open mouth. According to Michael (1993), it is usually solitary, but is rarely seen in aggregations. It apparently is rather sluggish, at least during the daytime, and is more active at night as are nurse sharks (Ginglymostomatidae) or when motivated by the presence of food. Because of its rather slender, flexible body and caudal fin it is able to squirm into narrow cracks, crevices and channels while searching for food. In captivity, it spends most of its time resting on the bottom (at least during the day), but becomes active when food is introduced into its tank. An immature male zebra shark about 1.3 m long was observed by the writer on two separate occasions in a large tank at the Waikiki Aquarium (February 2000). It sat on the bottom of its tank in the evening on one day but became highly active during feeding time in the early afternoon on a subsequent day. It swam about as fast as the 1.1 to 1.2 m long blacktip reef sharks (Carcharhinus melanopterus) that it was quartered with (speed estimated at 1.0 to 1.5 m per second), and during a half-hour's observation stayed near the top of the tank and swam continuously. It swam strongly, with prominent anguilliform undulations of its body and tail, and showed much manoeuvring and considerable agility while swimming. The shark broke the surface with its caudal fin on a few occasions, churning the water, but it was not obvious if it was using its tail in any special way. The caudal fin was held at a low but noticeable angle to the body axis. The elongated caudal fin seems less likely to be used as a weapon to herd and stun small fishes than the caudal fins of threshers (Alopiidae), but could be used during social activities, including courtship, as well as for facilitating entry into tight spaces. Oviparous, laying eggs in large (17 cm long, 8 cm wide and about 5 cm thick), dark brown or purplish black cases with fine lateral tufts of hair-like fibres, which serve to anchor the cases to the substrate. Probably lays more than one or two eggs at once, as four fully formed, encased eggs were found in one oviduct of an adult female. Feeds primarily on molluscs (gastropods and bivalves) but also crustaceans (crabs and shrimp), small bony fishes, and possibly sea snakes.

Regularly taken in inshore fisheries in Pakistan, India, Thailand, Malaysia, Taiwan (Province of China), and elsewhere where it occurs. It is caught in bottom trawls, in floating and fixed bottom gillnets, and with longlines and other line gear. It rarely takes baited hooks. The meat is utilized fresh and dried-salted for human consumption; livers processed for vitamins; fins dried and processed for the oriental sharkfin trade; and offal utilized for fishmeal. This is a hardy shark, readily kept in captivity and is an attractive and lively aquarium exhibit. It is currently kept in several public aquaria in Australia, Japan, Portugal, Singapore, Spain, and the United States. Conservation Status : The conservation status of the zebra shark needs assessment, as it may have declined in areas such as the Gulf of Thailand where it was formerly more common. Also, it may have been adversely affected by the widespread use of explosives and poisons to fish out reefs in the eastern Indian Ocean and western Pacific as with other reef sharks. It is not known how this shark figures in and is influenced by the international aquarium trade. Although the adults and subadults can only thrive in large public aquaria, as with nurse and tawny sharks, the very attractive newly-hatched young are sufficiently small to live in the tanks of private collectors.